Metallic holding elements in plastic housings serve to hold or transfer forces, for example, torques, when the plastic housing is being affixed to a carrier or a lid on the plastic housing. In general, holding elements of this nature should enable sufficient anchorage in the surrounding plastic housing, without creating the risk of weakening or even destroying the surrounding plastic housing when applying the holding element or force impact on the holding element. On the other hand, the holding elements must be constructed in such a manner that as little metal material and thus ultimately also as little weight as possible is required, and that they can also be produced at low cost.
Thus, for example, a load introduction element can be derived from DE 10 2012 215 587 A1, wherein a sheath surface is equipped with a contour which features indentations.
A supporting sleeve is known from EP 1468199 B1 and an affixing means is known from EP 2368051 B1 which also feature comparable forms. US 2005/0095078 also presents a blind rivet which already features undercuts in its basic form, which are then further deformed by a force impact on both sides.
A self-punching nut element for pressing into a metal sheet part is known from DE 10 2009 039 817 A, in which the nut element punches an opening into the metal sheet in a self-punching manner, and thereby deforms the displaced metal of the sheet into a groove that surrounds the nut element, and thus also an undercut.
In production technology terms, holding elements with such indentations are complex to create and are therefore expensive, and such a strong deformation as would be necessary to displace the plastic material into such undercuts when pressing into plastic openings, in particular plastic domes with correspondingly limited wall thicknesses, is not possible, and there is a risk that the walls might crack.
A construction element connection made from a metallic element and at least one planar element made of fiber-reinforced plastic is known from DE 297 18 724 U1, in which the holding area is free of incisions, indentations or undercuts, and also corners which are rounded off in profile are also connected through straight edges. However, there the holding element always features a connection section, on which the element is connected to an additionally required further metallic element through spot or plug welding, i.e. it is precisely not primarily affixed via pressing in. Furthermore, said construction element connection is not provided in order to realize a screw fitting to be affixed to it. Additionally, a metallic insert is known from DE 103 19 978 A1 in which the insert is precisely not intended to absorb torques, but with an elongated hole form enables a tolerance compensation between a majority of bore holes, which are arranged on a line accordingly. The profile of the hole in the plastic is adapted accordingly to the profile of the insert.
Additionally, a lead-free material should be suitable for use as far as possible, in order to reduce the pressure on the environment, although several of the known forms require machine processing and thus also a certain amount of lead in the material of the holding element.
The production of the plastic housing is also simplified when the holding element does not have to be overmolded with the material of the plastic housing as an insertion part, but can simply later be pressed in an opening. For this purpose, holding elements with a cylindrical holding area are known, for example.
Then, however, such a holding element with a larger excess size must be pressed into a corresponding opening of the plastic housing, which in turn increases the required edge in the plastic housing around the opening.
In particular when forming a plastic dome protruding from the plastic housing to hold the holding element, this is extremely undesirable, since the width of such a plastic dome increases the size of the plastic housing compared to a circuit board to be arranged in the plastic housing. To the extent that the circuit board should also be machined with the plastic dome, the circuit board surface available for electric construction elements would also be reduced.
All of these requirements therefore contradict each other and priorities must be decided accordingly. As such, it is desirable to present a particularly suitable holding element. In addition, other desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.